Review of three clusters of COVID-19 in Singapore, found that serology testing to establish past infection helped identify connections between clusters. Authors suggest that serology testing can have a crucial role in identifying convalescent cases or people with milder diseases.

SPS commentary:

A related commentary highlights that this investigation exemplifies the failings of RT-PCR as a sole diagnostic method in surveillance, because of its inability to detect past infection, and the added value of serological testing, which if captured within the correct timeframe after disease onset can detect both active and past infections. Serological analysis can be useful for contact tracing in urban environments and linking clusters of cases retrospectively to delineate transmission chains and ascertain how long transmission has been ongoing or to estimate the proportion of asymptomatic individuals in the population. It concludes that “Although RT-PCR diagnostics will still be vital for identifying acute infection, as the SARS-CoV-2 pandemic continues to spread and cases accumulate, serological testing and data will prove increasingly important to understand the pandemics' past and predict its future”.